Generally, the tents also include an inner room covered by said roof element serving as a shelter area.
In the summer, it has been observed that the temperature in these shelter areas exposed to the sun, in particular in the inner rooms, is higher than the temperature outside said shelter area, also designated in this text as the ambient temperature. A temperature difference has thus been measured, as an example at European latitudes, of up to 15° C. between the temperature of the air in the upper areas of the inner room and the temperature of the ambient air outside said tent-type article. Furthermore, it has been observed that the presence of thermal radiation in the inner room implies that the temperature felt (radiant temperature) by a user is higher than that actually measured in that room, which further accentuates the heat-related discomfort.
As a result, the user cannot remain in a tent or shelter exposed to full daytime sunshine without suffering even greater heat than that found outside said shelter area.
This temperature difference between the shelter area, in particular the inner room, and the atmosphere is due on the one hand to a key contribution by solar radiation, and on the other hand to insufficient ventilation of the shelter area, in particular the inner room.
A greenhouse effect has in fact been observed, related to the solar radiation, that occurs in the shelter area. The roof elements allow part of the incident solar radiation to pass, which is made up of ultraviolet (UV), visible, and near infrared radiations in the short wavelength range (from 0.2 μm to 2 μm). However, said roof elements do not allow the far infrared radiation with long wavelengths (greater than 5 μm) emitted and reflected by the shelter area, in particular through the walls of the inner room, the floor and optionally the users in that area, to escape outside said shelter area.
These far infrared rays reflected and emitted by the shelter area are then primarily captured in the latter and accumulate, thereby increasing the temperature inside the shelter area, as well as on the walls of the inner room when one is provided. This greenhouse effect is still more significant in an inner room.
Thus known from document US-2010/0059095 is a shelter with a reversible roof including a dark-colored winter face to heat the area of the shelter in which one or more people are housed and a summer face with a light color so as to cool the shelter area by reflecting the rays of the sun. In summertime, the light face makes it possible to prevent the temperature in the shelter area from being too high relative to the atmosphere. However, the temperature in the shelter area still remains very high, and there is a need to improve the thermal comfort of the users.
Also known in U.S. Pat. No. 3,244,186 is a tent comprising a summer part and a winter part that can be interchanged by a 180° rotation around its vertical axis without it being necessary to reverse the latter from the inside or the outside. In FIG. 1, U.S. Pat. No. 3,244,186 describes an alternative in which the tent is provided with a reflective coating on its outer face, for example, a reflective aluminum paint, and on its inner face, with a coating absorbing the heat, for example, a non-reflective black paint. During operation, when the tent is exposed to the sun's rays, the inner face absorbs and stores more heat than the outer face and retransmits more far infrared rays than the outer face, thereby creating heating of the shelter area that the tent covers.